Generalized Anxiety Disorder (GAD) is a highly prevalent chronic, under-recognized and under-treated psychiatric disorder, causing significant symptomatic and psychosocial impairment. Antidepressants such as imipramine, paroxetine, or venlafaxine XR, and the 5-HT1A partial agonist buspirone are considered presently the preferred treatments for acute and long term treatment. Despite the fact that GAD is a chronic disorder and frequently demands prolonged treatment with medication there is very little known about the benefits of long-term treatment. The efficacy of the SSRIs/SNRI class of medications such as paroxetine and venlafaxine XR is clearly evident in controlled, double-blind trials. However, there are only few studies that assess benefits of more than 8 weeks of treatment and no study for longer than 6 months. Therefore, it is not known for how long medication treatment should be continued to allow maximum symptom relief. In addition, it is unknown if, when,and how quickly symptoms return following a course of long-term medication treatment. This proposal tests, under double-blind conditions, two primary hypotheses. 1) 6 months of treatment with venlafaxine XR, followed by 6 months of placebo will be associated with significantly more relapse and lower levels of remission than treatment with venlafaxine XR for 12 months. 2) Treatment discontinuation after 6 months of venlafaxine XR therapy will be associated with significantly higher relapse rates than treatment discontinuation after 12 months of venlafaxine XR therapy. Following open label treatment with venlafaxine XR for 6 months approximately 165 patients will be available to be randomized into the relapse part of the study. Randomization will be stratified by severity of secondary depressive symptomatology at baseline and level of clinical global improvement obtained after 6 months of venlafaxine XR therapy. This study will allow the examination of relapse rates after 6 and 12 months of venlafaxine XR treatment as a function of improvement status, level of depressive symptoms at baseline, lifetime history of MDD, chronicity of GAD, and length of venlafaxine XR therapy (6 vs. 12 months). The proposed study will provide much needed data, lacking from the literature, about the value of long term medication treatment of patients with a DSM-IV GAD diagnosis.